1. Field of the Invention
The present invention relates to truck trailers.
2. Description of the Prior Art
Due to load restrictions on public highways, and general mobility and convenience considerations, ten wheel dump trucks are losing their popularity for certain applications. Typical dump truck, or spreader truck power plants have more than adequate capacity for hauling heavy loads, far exceeding that which may be conveniently loaded onto, and transported in the truck box under modern load restrictions. Consequently, trailers are frequently hitched behind a truck to carry additional payload which would exceed the limitation imposed on the axles of the truck. Such truck-trailer combinations have proven satisfactory for many applications but are impractical in many applications where spreading of the load, for instance asphalt, is required at the work site.
Most trailers do not incorporate the relatively expensive spreader attachments required for spreading of the load, and there is no practical means presently known for transferring the load from the trailer box to the truck box so that the truck box spreader may be conveniently utilized for spreading the trailer load. Consequently, there exists a need for a practical means for rapidly and conveniently transferring the trailer load to the truck box such that the truck spreader may be utilized in spreading both the truck load and the trailer load. To achieve this end, it is desirable to provide an efficient means for dumping the truck load forwardly from the trailer into the truck box.
It is further desirable that the trailer load be carried over the axle of the trailer, with such axle spaced a minimum distance behind the truck during transport to the job site. The load must then be shiftable forwardly on the trailer to a location adjacent the truck box for direct dumping thereinto.
It is known to provide dual purpose trucks which dump both forwardly and rearwardly. One such dual purpose dump truck which is capable of being used as a sander or spreader is disclosed in U.S. Pat. No. 3,620,458 to Albert Rath, issued Nov. 16, 1971. This truck includes a load supporting frame on which a dumping box is mounted. The dumping box is capable of selective pivotal connection either at its rear or at its front end to the frame, and toggle/cylinder means are provided for urging a central point of the box upwardly with respect to the frame, in either mode of pivotal attachment. When the rear pivot is connected, energization of the cylinder raises the box in the normal dumping mode in which the contents slide to the rear. When the forward pivot is connected, raising of the dump box gives it a forward slope and the contents thereof slide toward the front.
Other dual purpose dump box construction is shown in U.S. Pat. No. 4,056,283, issued Nov. 1, 1977. Forwardly and rearwardly dumpable truck boxes typified by these prior art patents, while satisfactory for their intended purposes, would not perform satisfactorily as forwardly dumpable trailer boxes since loading requirements dictate that the trailer load during transportation be shifted so far rearwardly on the trailer frame that simply dumping such load forwardly from its transport position on the trailer axle would not serve to place the trailer load in the truck box.
Another style of a forwardly dumpable truck box is shown in U.S. Pat. No. 2,697,609 to S. J. Chase et al, issued Dec. 21, 1954. Again, while serving its purpose of shifting the load forwardly to a forwardly located spreader, such an arrangement would not afford the desired object of this invention wherein the load is to be transferred from the trailer box to the truck box.
Other objects and advantages of the present invention will become apparent from a consideration of the following detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings.